This invention relates generally to the field of load-lifting cranes, and more particularly to a counterweight installation apparatus and method for such cranes.
A conventional method of installing counterweight on a crawler-mounted crane consists of positioning the separate counterweight sections on the ground, backing the crane upperworks up to the counterweights, lowering the gantry to allow the counterweight linkage to be attached to a counterweight section, raising the gantry and the counterweight section to a position wherein the counterweight section may be attached to the counterweight support on the rear of the crane upperworks, and attaching the counterweight section to the aforementioned counterweight support. This procedure is repeated until the desired number of counterweight sections are attached to the crane upperworks. This procedure has been used for some truck-mounted cranes as well.
A relatively new technique for installing counterweight on truck-mounted cranes was devised by Link-Belt. The Link-Belt design utilizes hydraulic cylinders with attached linkages for raising counterweight sections from a crane carrier deck. This design, as opposed to the conventional design, eliminates the need for the counterweight sections to be positioned on the ground in order to be attached to the crane upperworks. Rather, in the Link-Belt design, the counterweight sections are located on the carrier deck and the crane rotates to the location necessary for the counterweight sections to be attached to the crane upperworks (i.e., the rear of the upperworks facing the counterweight sections). The above-described hydraulic cylinder and linkage arrangement raises and attaches the desired number of counterweight sections to the crane upperworks.
While the above-described apparatuses and methods for installing and removing crane counterweight are adequate for some purposes, a more convenient counterweight installation and removal apparatus is desired for other truck-mounted cranes. Truck-mounted cranes are not as mobile as crawler-mounted cranes, and they typically are higher off the ground than crawler-mounted cranes. Therefore, the counterweight installation and removal apparatus and method of the present invention is designed to accommodate the lack of maneuverability and the height of truck-mounted cranes. Necessarily, this apparatus is designed such that the counterweight moves beyond the crane upperworks after it has been removed, so that the crane upperworks is able to rotate freely.